This investigation will examine early vocal development in prelingually deaf children who receive multichannel cochlear implants before 5years of age. The Continuity model of phonological development (Locke, 1983) allows us to predict that young implant recipients will produce increasingly more complex and speech-like vocalizations before they say real words and that the phonetic content of their vocalizations from parent-child interactions will be recorded before implantation and on a monthly basis for two years after implant activation. The scale of Vocal Motor Development (Nathani, Ertmer, & Stark, 1998) will be used to classify vocalizations, assign developmental levels, and determine rate o attainment of vocal milestones such as canonical babbling, disyllables, jargon, and spoken words. Vocabulary and phonological analyses will be implemented after the child has produced approximately 50 spoken words so the relationship between prelinguistic vocal development and phonological and lexical growth can be explored. These analyses will help to determine whether prelinguistic speech patterns predict later phonological and lexical development and should lead to research based intervention strategies for the increasing number of children who receive implants at a young age. This work will also provide a new perspective on the role of babbling in phonological development. Children who are implanted before 3;0 are expected to babble more than those who receive an implant between 3;0 and 5;0. If babbling is not critical for speech development there should be little difference in the lexical and phonological development of proficient babblers and those who babble on a limited basis. Conversely, if babbling plays an important role in speech development then proficient babblers should demonstrate more rapid lexical growth and greater phonetic diversity than their counterparts. In addition to bolstering theoretical perspectives, examination of the relationship between babbling and oral language development "will be helpful in determining the benefits of early implantation and therefore guiding future policy" with regard to minimum age requirements for implantation (NIH Consensus Statement on Cochlear Implants, 1995, p.18).